Spark-plug.



O. BATEHOLTS.

SPARK PLUG.

APPLIUATION FILED MAY 4. 1908.

91 3,453, Patented Feb. 23, 1909.

WITNESSES IN VEN TOR.

A TTORNE Y.

CLINTON BATEHOLTS, OF PITTSFIELD, MASSACHUSETTS.

SPARK-PLUG.

Specification of Letters Patent.

Patented Feb. 23, 1909.

Application filed May 4, 1908. Serial No. 480,831.

To all whom it may concern:

Be it known that I, CLINToNBATEHoLTs, a citizen of the United States of America, and residentv of Pittsfield, in the county of Berkshire and State of Massachusetts, have invented certain .new and useful Improvements in Spark-Plugs, of which the following is a full, clear, and exact description.

' This invention contemplates the provision of a simple, cheap, and efiicient spark plug for explosive engines in which the electrode rod, extending axially through, and projecting endwise beyond, the ends of the metallic shell or body of the plug, is supported by and separated from the metallic shell by a body of plastic insulating material molded in its interposed position, so as to be permanently engaged with the internal walls of the meta 1c shell, and also molded closely around and in intimate permanent contact with and immovably supporting, the rod, whereby' Figure 1 1s a central longitudinal section Fig. 2 is an inner end view side view.

Similar characters of reference indicate corresponding arts in all pf the views.

The spark liig comprises an annular metallic shell A iaving a portion a of standard tapered and screw threaded formation and provided at its inner end with a terminal extension or electrode 6. The appliance furthermore comprises an electrode rod B havand Fig. 3 is a ing its extremities projecting beyond the.

ends of the shell, its outerone being screw threaded, as shown at d; and the said shell and electrode rod have shoulders f and 9 respectively in the internal wall of the shell and circumferentially of v the intermediate portion of the rod,s aid shoulders being practicably constituted by grooves, as shown 1n Fig. 1. The s ark plug, furthermore, comprises a body of plastic insulatingmaterial molded within and ermanently engaged. and interlocked wit the internally shouldered Wall of the metallic shell, extendspark coil. 4

ing at both its extremities beyond the ends of the shell, but terminating at oints removed from the end of the electro e rod and molded closely around, permanently engaged and interlocked with and supporting the rod throughout the entire length of such molded plastic body, which latter, as above stated and shown, is considerably longer than the length of the metallic portion A of the plug, so that while the rod has an unusually long bearing and supporting connections through the molded plastic insulating body, the body itself is only subject to the constrictions on the shell under temperature changes for but a fraction of the length of the molded body,'a portion of the reduced inner extremity of the molded body havin as shown at h, a separated relation to tile metallic shells.

The outwardly projecting portion of the molded plastic body is made with a shoulder enlargement 11 en agin theouter end of the shell, and a metal ic co ar j is enga ed about the outer extremities of the electro e rod and is set against the outwardly rojecting end of the insulating body, while the binding nut 7c screw engages on the outer thread-ed ex.- tremity of the electrode rod, with which the collar 7' is in metallic connection, for the confinement in its proper place of the conductor whichis a In the-construction of the plug, the shell A advanta eously may be of brass or iron,

the electro e rod of steel, the collar and nut of brass or iron and the electrode point at the inner end of the plug of German silver. The molded lastic body is composed of a composition w ich when hardened is as refractory as granite 'and when finished'as to its projecting extensions, is as smooth as soapstone.

1. A spark plug com rising'an annular externally screw threade metallic shell having a terminal extension at the inner end thereof, an electrode rod arranged axially within said metallic shell, and having its extremities rojecting beyond the ends of the shell, said shell having shoulders at its internal wall, and the intermediate portion of the rod having circumferential shoulders, and a body of plastic insulatin material molded within the'shell and aroun the electrode rod and having permanent interlocking engagements with the shoulders thereof.

part of or an extension from the engaged and interlocked with, and support-.

2. A spark plug comprising an annular externally screw threaded metallic shell having a terminal extension at the inner end thereof, an electrode rod arranged axially within said metallic shell, and having its exing, the electrode rod throughout the entire length of such molded plastic body.

3. A -sparkplug comprisingan annular externally screw threaded metallic shell having a terminal extension at the inner end thereof, .an electrode rod arranged axially within said metallic shell, and having its extremities projecting beyond the ends of the r shell, its outer one being screw threaded, said shell having shoulders in its internal wall and the rod having circumferential shoulders, a-

body of plastic insulating'material molded Within and permanently enga ed and interlocked with the internal shou dered wall of the shell, extending at 'both its extremities beyond the ends of the shell, terminating within the ends of the rod and molded closely around, permanently engaged and interlocked with, and supporting, theelectrode rod throughout the entire length of such molded plastic body, and having its projecting portion located next toand extended outwardly beyond the metallic shell made with a shoulder enlargement engaging the outer end of the shell, a metallic collar engaged about the outer extremity of the electrode rod and resting against the outwardly projecting end of the molded plastic body, and a binding nut screw engaged on the threaded extremity of the rod adjacent said metallic collar.

Signed by meat Pittsfield, Mass, in presence of two subscribing witnesses.

CLINTON BATEHOLTS. 

